Electronic equipment is often housed in a metal framework called an equipment rack. A typical equipment rack contains multiple bays, each holding a unit of electronic equipment, such as a server or a switch. Racks are generally available in standard sizes. Typically, each equipment unit occupies one of the bays and is secured to the rack with screws. To install a unit of equipment in a four-post rack, for example, a side rail is secured to each side of the unit of equipment. This assembly is then attached to the front and back vertical structural members of the rack, herein referred to as mounting rails.
An example of a rack 10 appears in FIG. 1. The rack 10 has a plurality of stacked units of electronic equipment 12. Cooling fans and other mechanical mechanisms (not shown) installed within the rack 10 move air in a direction designed to remove heat from the equipment housed within. Many racks produce front-to-back airflow, whereas many others produce back-to-front airflow.
Data centers typically have several racks of electronic equipment and often employ an overall cooling strategy based on a uniform airflow direction among its racks. Depending on a particular rack airflow strategy, the various units of electronic equipment in such a datacenter environment should have similar airflow direction. Notwithstanding an overall strategy, each unit of electronic equipment 12 housed within the rack 10 usually employs fans 16 to generate an internal airflow that cools the electronics housed within. These fans occupy a fixed position within the equipment and produce a particular airflow direction. Such airflow direction 18 may be from the front to the back of the equipment (FIG. 2A), from the back to the front (FIG. 2B), from side to side (FIG. 2C), or from side to back (FIG. 2D). The direction of airflow produced by any given unit of electronic equipment may not be consonant with the airflow direction produced by the rack. Once configured to provide a particular direction of airflow, though, the electronic equipment cannot change that direction of airflow without undergoing redesign.
Dissimilar directions of airflow produced by the rack and the various units of electronic equipment can produce an undesirable condition in which hot air circulates within the equipment rack. For example, as shown in FIG. 3, consider that the rack 10 exhausts hot air (arrows 20) at the back of the rack, whereas the electronic equipment 12 intakes air (arrow 22) from the back in accordance with its back-to-front airflow. Such a condition can cause the internal temperature of the equipment 12 to rise and, in extreme cases, render such equipment inoperable. However, if the electronic equipment is not suited for the airflow direction required in the rack, then a different unit of equipment is needed or the unit of equipment needs to be redesigned, which may be a costly venture that increases the price of the resulting product, rendering it competitively disadvantaged.
In addition, units of equipment employing a side-to-side cooling airflow generally cannot be installed in a rack employing a front-to-back cooling environment. For instance, as shown in FIG. 4, the installation of a unit of equipment 12 within the rack 10 often entails the use of a pair of side rails 28-1, 28-2 (generally, 28), one side rail along each sidewall of the rack 10. The sides of the unit of equipment 12 couple to these side rails 28. However, as illustrated in FIG. 5, the side rails 28 can obstruct the free flow of air moved into and out of the unit 12 by the fans 16 (the outline of the fans are drawn in dashed lines to show that the side rail 28 effectively covers them).